Storage tank and method of constructing same



Dec. 24, 1946. w. NEFF 2,413,243

STORAGETANK AND METHOD OF CONSTRUCTING SAME I Filed March 7, 1944 2Sheets-Sheet 1 @www W. NEFF Dec. 24, 1,946.V

STORAGE TANK AND METHOD OF CONSTRUCTING SAME 2 sheets-sheet 2 FiledMarch 7, 1944 www Patented Dec. 24, 1946 STORAGE TANK AND IWETHOD FCONSTRUCTING SAME Wallace Ne, Los Angeles, Calif.

Application March 7, 1944, Serial No. 525,475

9 Claims.

This invention relates to improvements in concrete tanks for the storageof gasoline, fuel oil, water and like liquids and the method ofconstructing the same.

Shortages in critical materials such as steel has limited, if notentirely prohibited, the construction of gasoline, fuel oil and waterstorage facilities urgently needed for civilian use in many sections ofthe country. Moreover, greatly increased military use of gasoline andfuel oil and the mobility of modern warfare have created serious supplyand storage problems, particularly in the rapid construction of adequatestorage facilities at advanced bases and under conditions of extendedlines of supply. While attempts have been directed to the solution ofthe problems attendant to the above circumstances, such have not beenentirely successful because, even where gasoline and oil storage tankswere constructed of concrete, they were of the conventionalsteelreinforced construction requiring shipment to the site ofsubstantial amounts of steel necessary to their erection, and theirconstruction moreover followed the slow methods characterizing Y theusual practices of concrete construction.

The present invention contemplates and provides improved storage tanksfor gasoline, fuel oil, water and such liquids required to be stored,which may be constructed of readily available materials throughout andaccording to an improved method of construction which is economical,extremely fast, and capable of being carried out with a minimum ofequipment by available, relatively unskilled labor. More specifically,the

invention has for an object the provision of improved concrete tankssuitable for the storage of gasoline, fuel oil and Water which are ofsuch form and inherent structural strength as to require little or nosteel reinforcement and which, moreover, can be site-fabricatedsubstantially throughout from materials which vto a large extent arelocally available, and with equipment which is sufficiently light inweight that it can be supplied by air to the erection site. Theinvention further proyides a novel concrete storage tank of spherical,semi-spherical or even cylindrical shape, of a type which is erected onan lnterior pneumatic form of the required shape and size and whichemploys the form, the latter being left in the completed structure, as aleak-proof container for the liquids to be stored, the container beingin turn supported' by the concrete structure erected thereon. Accordingto the invention, there is moreover provided a novel type of pneumaticform for the erection of structures as aforesaid which is relativelysimple and inexpensive in fabrication, and which is sufficientlyflexible and light in weight that it can be flown to an erection site ina small package.

Other objects will be in part ovbious and in part hereinafter pointedout in connection with the following analysis of this invention whereinare illustrated in detail selected embodiments of the invention.

In the drawings- Fig. 1 is a part elevational, part sectional view of agasoline storage tank according to the in vention;

Fig. 2 is a detail illustrating the preferred manner of securing theform to the concrete shell erected thereon in such manner that itprovides a permanent inner liner therefor; and Fig. 3 is a partelevational, part sectional view of another form of storage tankaccording to the invention.

Concrete storage tanks of the type to which the present inventionpertains are erected generally in accordance with the methods ofbuilding construction disclosed and claimed in my prior Patents#2,270,229, dated January 20, 1942, and #2,335,500, dated November 30,1943, and in my pending application, Serial No. 451,056, filed July 15,1942. I'n the practice of such methods, a concrete shell is built up byapplying a continuous layer of wet concrete over the exterior surface ofan internal pneumatic form of size and shape such that upon inationthereof it assumes the size and shape of the interior of the desiredstructure and in such. manner that the so applied concrete remains inplace on the form without the aid of an external form and upon settingprovides a self-sustaining shell.

According to the present invention, a pneumatic form as aforesaid may beof full spherical shape, or may be of semi-spherical or cylindricalshape of either the closed or open bottom type in accordance with myprior disclosures, and is of course provided with means by which it canbe suitably anchored to a foundation slab prior to inflation. Followinginflation, and especially when Working with low inflation pressures ofup to 2 oz. per sq. in., a preliminary shell functioning as a secondaryform is preferably first built up on the pneumatic form as by sprayingthe exterior surface of the form with a fast-setting plastic materialsuch as gypsum plaster or a wet mixture of gypsum, cement and sand insuitable proportions as to render it fast-setting, to a continuous layerthickness of approximately 1%; in. The ination pressure is maintaineduntil the thin layer of plastic material has set, whereupon there isprovided a self-sustaining shell capable of sustaining the load of theconcrete which is thereupon applied thereover to the desired thickness.The concrete may be placed by the conventional troweling method or, whenthe necessary equipment is available, by the guniting method. Where itis desired that the final shell have a contour approaching that of asemisphere, but with its pole flattened and its side walls bulgedoutwardly, the plastic material forming the pre liminary shell may befirst applied to the top portion of the form in such manner that theload thereof effects a controlled deformation of the form, according towhich its pole is fiattened and its side walls bulged outwardly. As theplastic material is applied to the side portions of the pneumatic form,it follows the deformed contour thereof, with the concrete subsequentlyplaced over the preliminary shell in turn following the contour of thelatter. It is also possible to give the nal structure the shape of apeaked dome, in which case the plastic materialis applied as by sprayingfirst the side portions of the form so that the load of the appliedmaterial has the effect of weighting-down the side portions and therebycausing the top portion of the form to deform upwardly, with the resultthat the top portion of the final structure is peak-shaped.

A form according to the present invention is fabricated from readilyavailable fabric materials, among which may be noted nylon, tire cordfabric, highthreadcount cotton muslin, and cotton duck, which materialscan be rendered air-tight at the relatively low iniiation pressures towhich the form is inflated. The form is left in the shell after thelatter has set, suitable means being provided to tie the form to theshell, thus to prevent the latter from stripping away from the shellwhen the inflation pressure is released. I have discovered that bycoating such fabric materials with a synthetic rubber such as Thiokol orBuna, not only is the material rendered air and liquid tight but also itis rendered resistant to the solvent effects of modern high octanearomatic gasoline. Accordingly, when a form fabricated of materialtreated as aforesaid is left within the shell, the form acts as aleak-proof fabric container for liquids such as gasoline stored-withinthe same,

the container being in turn structurally supported against the load ofthe gasoline or other liquid by the concrete shell erected thereonaccording to the invention. 'I'he same or equivalent proofing substancesmay be employed to treat the fabric in the case of tanks designed forthe storage of fuel-oil and water, for example.

In the drawings wherein are shown two forms of storage tanks selectedfor the purpose of illus-v trating the present invention, a shell I(Fig. 1') of semi-spherical shape is shown as erected on the pneumaticform II, in accordance with the methods of construction previouslydescribed. In the illustrated embodiment, the form II is ofsemi-spherical shape, having a fiat bottom I2 supported on a circularfloor slab 3, a suitable waterproof membrane I4 being disposed betweenthe iioor slab and the ground to protect the slab from the deleteriouseffects of moisture. Preferably, the floor slab is sloped downwardlytowards its periphery to permit water collecting in the bottom of allgas tanks to be drained off from time to time. As shown, the form isprovided along its periphery with a securing apron or fiap I5 which isof depth to extend below the under 4 corner of the fioor slab, the aproncarrying a. tie cord for securing the apron and hence the form to theslab. Other means of anchoring the form to the iioor slab may of coursebe substituted.

Preferably, the form is provided with means such as buttons, keys orflap-like extensions to tie itself to the concrete which is subsequentlyapplied thereover. In" Fig. 2, such means are shown to take the form of1/2" or :5/4" keys I8 arranged, for example, at 14" centers each way,and being embedded in the first applied coat or layer of the concrete orplaster, the keys I8 serving also as a means of gauging the thicknessthereof. Upon setting of this rst layer the keys as aforesaid provide amechanical bond between the form and concrete shell, and thus strippingof the form under its own weight from the shell upon release of theinflation pressure is prevented.

The form may be provided at its pole with a cylindrical appendix 20about which the concrete is built up as at 2| to provide a circular topopen for a fitting 22 of the desired type. Adjacent its bottom, the formmay also be provided with a similar appendix or tube 23 defining abottom opening through the structure for a drain fitting.

As shown in the drawings, the concrete is applied to a substantiallyincreased thickness along the base line of the structure and both alongand beneath the floor slab I3, thus to provide a circular footing I6 inwhich the form apron I5 and its tie cord is embedded.

A shell structure erected in accordance with the foregoing provides aninner liner or container of fabric for the liquid to be stored. Pai'-ticularly where the shell-form tank is employed for the storage ofhigh-octane aromatic gasoline, the fabric form is fabricated from amaterial which is resistant to the solvent effect of the gasoline, orthe form following fabrication may be treated with an aromatic gasolineresistant substance such as Thiokol or Buna, and the treated formemployed in erection. Or the untreated form may be shipped to the siteof erection, and following the construction of the shell as aforesaid,the interior surface of the form which is retained in the structure islined or coated with a resistant substance of the type indicated. In thecase of a tank designed forthe storage'of fuel oil or Water, the formmay be equivalently treated either before or after erection of the tankto render the form oilor waterproof. Accordingly, the lining orcontainer provided by the form within the shell is impervious to theparticular liquid to be stored therein. The outer surface ofthe tank maybe coatedA or sprayed with a suitable waterproofing substance, thus toprotect the same from the effects of weather if the tank is of theoverground type, or ground moisture if the tank is built underground.

It will be understood of course that the final thickness of the concretewall is such as to impart the structural strength'required to enable theshell to sustain not only its own weight but also the load of thegasoline or fuel oil contained within the same. Thus, in a storage tankhaving a iioor diameter of 22 feet, the interior cubicalspace of whichprovidesa storage capacity ofl approximately 20,000 gal., the shell wallalong'its upper portion will possess a thickness of the order of 3". Atits base line, this thickness is increased, as indicated, to enable theshell to support at its base line a hoop stress of 60 lbs. per sq. in.when filled. Due to the great structural strength of a concrete Wall ofsubstantially monolithic construction which extends along a continuouscurve or arch from two spaced points of support, no structuralreinforcement is required and hence storage tanks in accordance with theinvention can be erected without the requirement of steel reinforcement.Moreover, as the form is treated to render it impervious to gasoline,fuel oil, water or other liquid to be stored therein, the form preventsseepage of the gasoline, oil or other liquid contained Within theconcrete shell through hair cracks which may develop therein, and thusaids materially in overcoming the disadvantages incident to priormethods employed in steel and concrete tank construction.

Fig. 3 is illustrative of a spherical storage tank according to theinvention and of the form employed in its erection. Reference character30 indicates a pneumatic form of full spherical shape provided along itsequator with a depending apron 3| by which the form is secured bytemporary ties 32 to a foundation slab 33. The form may be provided atits top pole with an -appendix 34 and adjacent its bottom with anappendix 35 to define fitting openings, as described in connection withFig. 1. Suitable means (not shown) are provided on the exterior of theform to anchor the latter to the concrete spherical shell erectedthereon.

Upon inflation of the form, concrete is applied over the outer surfacethereof in the manner -indicated in the foregoing, to a depth ofapproximately 3" for a shell 36 having a 9 ft. radius and a capacity ofapproximately 22,500 gallons, As shown, the space between the bottompole of the shell and the slab is filled in with concrete to a thicknesssuitable to the formation of a foundation 38 which gives verticalstability to the final structure.

The spherical form is fabricated from materials resistant to gasoline,fuel oil, Water and like liquids, or is treated during fabrication witha substance rendering the fabric thereof resistant to such liquids asaforesaid. Alternatively, the form may be supplied untreated, andfollowing erection of a spherical concrete tank structure thereon, theinterior surface of the form is then sprayed or otherwise coated withthe resistant or proofing substance.

It is also within the purview of the invention to form the tankscylindrical on a pneumatic form having corresponding cylindrical shapeupon inflation thereof.

Tanks in accordance with the foregoing may be built overground, althoughthey may readily be erected in a construction pit, as indicated in Figs.l and 3, and thereupon covered with earth where conditions require ormake advisable the provision of underground storage facilities.

The invention as above described achieves the objectives of providingconcrete storage tanks for liquids such as gasoline and fuel oil, whichmay be erected from readily available materials, by a simple andinexpensive construction method, and with the minimum of equipment. Dueto the fact that the method employed in constructing such tanks isextremely fast, the estimated construction time being approximatelyeight hours, it will be appreciated that the invention not only makesfor the inexpensive and fast construction of permanent storage tanks butis also particularly applicable to storage tanks constructed for iii)temporary use as required, for exampleAn supplying the demands of mobilewarfare. Moreover, when used for military purposes, storage tanks inaccordance with the invention are capable of being readily camouflagedand may, if desired, be erected in excavations and thereupon covered orpartly covered with earth to render them substantially undiscerniblefrom the air.

As many changes could be made in carrying out the above constructionswithout departing from the scope ofthe invention, it is intended thatall matter 'contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

I claim:

1. A storage tank for gasoline, fuel oil and like liquids comprising aconcrete shell-form structure consisting of a continuous andload-sustaining layer of set and substantially unreinforced conceretewhich in section extends along a continuous curve between transverselyspaced points on the structure floor line, and a fabric membercharacterized by its prefabricated construction and a shape and sizecorresponding to that of the structure interior, said member beingbonded to the inner Wall of said structure in the setting thereof andproviding, a unitary inner container for liquid within the structure andwhich is supported under the load of the liquid by the concretestructure.

2. A storage tank as set forth in claim 1, wherein the fabric membercarries a coating rendering it airproof and also resistant andimpervious to liquid contained therein.

3. A storage tank for gasoline, fuel oil and the like comprising aconcrete shell-form structure, a fabric member disposed within thestructure and being characterized by its prefabricated construction anda shape and size corresponding to that of the structure interior, saidfabric member carrying means on its outer surface which is bonded to theconcrete shell-form structure during the setting of the concretethereof, whereby said member is permanently secured within and againstthe inner face of said structure and provides a unitary inner containerfor liquid within the latter, which is supported under the load of theliquid by the concrete structure.

4. A storage tank as set forth in claim 3, wherein the fabric membercarries a coating rendering it airproof and also resistant andimpervious to liquid contained therein.

5. The method of constructing shell-form concrete storage tanks forgasoline, fuel oil and like liquids, which comprises the steps ofanchoring to a suitable foundation a pneumatic form made from fabricmaterial and of size and shape such that upon inflation it assumes thesize and shape of the interior of the tank and which is provided on itsexternal surface with bonding means, inflating the form, and applyingconcrete over the external surface of the form in such manner that theapplied concrete embeds the bonding means and remains in place on theform during setting Without the aid of an external form, whereby toprovide upon setting a self-sustaining concrete shell-form tank having afabric lining bonded to its inner surface.

6. The method as set forth in claim 5, wherein the fabric form istreated with a substance rendering it impervious and resistant to liquidcontained in the tank.

7. The method of constructing shell-form concrete storage tanks forgasoline, fuel oil and like liquids, which comprises the steps ofanchoring to a suitable lfoundation a pneumatic form made from fabricmaterial and of size and shape such. that upon inflation it assumes thesize and shape of the interior of the tank and which is provided on itsexternal surface with bonding means, inating the form, applying concreteover the external surface of the form in such manner that the appliedconcrete embeds the bonding means and remains in place on the formduring setting without the aid of an external form, whereby to provideupon setting a self-sustaining concrete shell-form tank having a fabric1ining bonded to its inner surface, and coating the inner surface of thelining with a substance rendering it impervious and resistant to liquidcontained in the tank.

8. A pneumatic form comprising an inflatable pneumatic body of size andshape such that upon inflation it assumes the size and shape of theinterior of a shell-form concrete structure adapted to be erectedthereon for the storage of gasoline, fuel oil and like liquids, saidfabric body carrying a substance rendering it liquid-proof and resistantto such liquids whereby when left within a structure erected thereon thefabric body is adapted to provide a liquid-proof container Within thestructure, and being provided on its exterior surface with means forsecuring itself to the structure erected thereon.

9. The method of constructing shell-form concrete storage tanks forgasoline, fuel oil, and like liquids, which comprises the steps ofanchoring to a suitable foundation a pneumatic form made from fabricmaterial and of size and shape such that upon inflation it assumes thesize and shape of the interior of the tank, inflating the form, andapplying concrete over the external surface of the form in such mannerthat the applied concrete remains in place on the form during settingWithout the aid of an external form and that the form secures itself tothe concrete of the shell in the setting thereof, Whereby to provideupon setting a self-sustaining concrete shell-form tank having its innersurface lined with a fabric lining.

WALLACE NEFF.

